All the difference
by Lotten
Summary: When Harry is sent back in time to the school days of his parents, he learns to see both them and himself in a different light. And when he now can change everything that is wrong in his life, will he, even if he has to sacrifice everything that's right?


**A/N: **...god, I'm stupid. ANOTHER fanficition to add to the oodles I haven't finished. Great job. But AL (i.e. my least popular fic) is soon finished, so maybe I'm learning? Anyhoo, I couldn't resist making my own stab at the ol' time-travelling thing.

Firstly: None of this is mine, and I am not making any money. Well, Professor Hunt _is_ mine, but I'm not making any money out of her either.

Secondly: This fic will contain slash, but the nature of it is a bit uncertain as for the moment, and besides, in most cases I don't like giving away what little plot I actually have, so my readers will usually have to be content with that there _will_ be slash, just unspecified slash.

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Chapter one

**Rewind**

* * *

Finally the war was over, and Harry felt like he could've slept for a decade. Only, there was no time for that. Between dodging terrorists- sorry, _journalists_, and trying to recount an at least reasonably coherent story to the Aurors, there seemed to be little time to while away taking it easy and waiting for the panicky buzz to fade from his head.

There were also some things he needed to do for personal reasons. He attended the memorial for the people who had died in battle, feeling empty and miserable as he watched George gaze hollowly at nothing at all; as he heard the heartrending sobs that came from Mrs Weasley; saw Collin's father collapse on his way from there, and had to be helped away by his wife and Dennis; as he saw the silent tears that etched their paths down Andromeda Tonks' cheeks as she held her grandson tightly in arms that trembled.

She met with Andromeda later, explaining that even if he was Teddy's godfather, he agreed that it would be a lot better if she cared for him, adding that if there was anything she needed, he would naturally be there. She had hugged him tight then, and called him a sweet boy in a voice that was thick with tears.

In the Entrance Hall there was now a large plaque with Snape's name on it, and under it was inscribed a snatch of a poem, strangely enough by William Wordsworth. Harry had stayed there for a while, tracing the swirling letters with his finger:

"_I listened till I had my fill:_

_And as I mounted up the hill,_

_The music in my heart I bore,_

_Long after it was heard no more."_

He did not know who had decided what the inscription was to be, he thought maybe McGonagall had been in charge of it, and it seemed oddly suitable.

And then, finally, came the task at the end of all others. After that, he would go home. He went slowly to Dumbledore's office, to look through it once before he left Hogwarts and hopefully never returned again. He found the pensive where he had left it on the desk; no one had bothered to move it. He saw Headmasters gazing at him from their portraits, yet Dumbledore was asleep in his, and that made it easier. Harry felt vaguely guilty at the thought of going through his stuff.

Snape had kept the office as Dumbledore had left it, and at first Harry wondered why that had not raised suspicion. But to the other Death Eaters it must've seemed like he was mocking Dumbledore by taking his place rather than what it truly was; a sign of deep respect. Harry walked among the beautiful, spindly contraptions, touching everything and remembering the first time he had come here; the many times that had followed, often in a time of danger or in the aftermath of some struggle.

In Dumbledore's bedroom he found a large bed which obviously hadn't been slept in in a long time; there was a fine layer of dust covering the bedcovers. Next to it stood a camp bed with rumpled bedclothes, and Harry supposed that Snape must've slept there. Connected to it there was a small office crammed full of books and an array of curious instruments, and in the next room he found what looked like a workshop. In the middle of it, on a table, was a huge, twisted contraption. Unlike the other instruments and devices there it was not beautiful, not graceful. It looked like it had been taken apart and put together a hundred times or more. Scattered around it were pieces of broken glass and misshapen metal. Fascinated, Harry reached out a hand to touch it, and as his fingers brushed against it, it began to hum softly. Intrigued, and not worried enough by the sound to stop, Harry continued to explore it, and as he touched a large bulb of glass at its centre, the whole thing began to glow in an eerie, pulsing red. He was overwhelmed by a feeling of deep regret as he suddenly recalled everything he wished he hadn't done, everything that he wished had happened differently, until finally he could once more hear his mother's frantic voice as she begged Voldemort to spare her son. Harry tried to pull away, but his body had gone cold and unmovable, and the light turned brilliant and terrifying before darkness came.

* * *

Harry was thrown backwards on cold marble floor, swearing under his breath as pain stabbed through his limbs. He looked around wildly, and as he found himself to be in the same workshop as he had been moments ago, he was relieved. The feeling brought on by the strange contraption had been very like a portkey, and he had been afraid that it had spirited him away from Hogwarts.

He stood up, and his relief faded quickly as he realised that there was light shining through the window and the sky outside was blue, not black. Had he fainted? What was the time? What had _happened_?

He heard the noise of someone approaching outside, and braced himself to be told off for scaring everyone, when the door opened and Harry nearly did faint for real. In the door, peering at him from over the rim of his half-moon glasses, was Dumbledore.

Harry looked wildly at where the contraption had been, wondering dazedly if Dumbledore had somehow managed to build a device that would bring him back from the dead. But that was impossible! Even the stone had only been able to bring fourth shadows...

His stomach clenched in dismay as he saw what he supposed was the contraption smashed into a thousand pieces.

"Who are you?" Dumbledore demanded to know, and Harry's attention snapped back to him. His mouth opened in disbelief.

"I... professor, I... You know who I am!"

He threw one more look at the shattered device on the table, and Dumbledore followed his gaze, his eyes narrowing.

"I think I broke it," Harry said, apologetically.

"No, you did not," Dumbledore replied; a bit faintly, Harry thought. "I did."

"You did, professor?" Harry was far too confused to do more than stare at him.

"You keep referring to me as 'professor', so it appears most likely that you know me as your Headmaster," Dumbledore mused aloud. "You seem unaware what has happened to you, so I shall assume that you travelled without my permission." He pinned Harry with a steely blue gaze. "This device you see behind you, did you touch it? Was it completed?"

"I... I think so, professor. I mean, I did touch it, and I suppose it was completed. It didn't look anything like it does now. But how-?"

"How could I have allowed myself to do that?" Dumbledore muttered, cutting him short, and Harry could clearly see that he was anguished. "And how come I allowed someone into this room if it indeed was finished? I would never... No." He looked up at Harry, now once again calm. "Where you come from, am I in fact dead?"

Harry gaped at him, unable to speak, unable to even think, but as Dumbledore gestured slightly impatiently at him he swallowed and forced the words to come. "You are... dead, professor. I saw you once after you had died, but not like this. What happened?"

Dumbledore sighed, looking disturbingly tired and old. "I am afraid that what has happened is that you have travelled backwards in time. How far – for how long, I do not know. And the reason you are here you can only answer for yourself. The device sent you here because here you have a chance to right your deepest regret."

It took a long time before Harry could figure out what to ask first; his head seemed full of clamouring voices. "What year is it?" he finally managed.

"It's 1976," Dumbledore replied, "and you have presently still not answered my question. Who are you? A future relation to the Potters, I should think."

"Harry Potter," Harry said faintly, his mind running ahead of him, drawing unbelievable conclusions. "I'm... I'm the son of James Potter, he must be a student here, sixth year..." Harry fell silent as Dumbledore's words finally sank in. His deepest regret... Could it be other than that his parents were killed on his behalf? Had he been sent here because he could change that at this point in time? And why? Why had Dumbledore...?

"Ariana," he breathed, understanding. "You built it so you could go back and save her."

Dumbledore became as white as parchment and shied away from Harry as though he had hit him. "You... you know?" he mumbled in disbelief, and in his eyes were a horror that Harry remembered only from once before, when Dumbledore had drunk the potion in Voldemort's cave. "I told you?"

"N-no, professor," Harry said, feeling far too ashamed to meet his gaze for long. "Aberforth, your brother, he told me."

Dumbledore nodded slowly, apparently fighting for control over himself. "I see. I'm sure he had a good reason, he never would have mentioned it otherwise... but do not tell me anything else about this. If we manage to send you back it is best if I know as little of the future as possible, since I will have to make myself forget all about it."

Harry nodded, and then felt his stomach sink as he realised what Dumbledore had just said. "_If_ you manage to send me back, professor?"

The old man looked very serious. "You must understand, Mr Potter, that the contraption you used to travel here was only designed to allow me to travel backwards in time. I had no intention of returning once I had helped my sister; after all, who knows what I then would have been returning to? Changing such a thing would mean changing me, what I became, and, alas, that would amount to a large portion of history being changed. That is why, every time I have been foolish enough to try to finish the device," he gestured at the clutter of glass and metal behind Harry, "I have soon enough realised the imprudence of it, and destroyed it." He sighed, looking worn and tired. "Unfortunately, my genius and my folly have all too often gotten the best of me, and every time I've gotten a little bit further towards the completion of a thing that I should never have allowed myself to conceive in the first place."

"So... are you saying it's impossible?" Harry asked, feeling numb with shock.

"I do not know," Dumbledore admitted. "Firstly, it is impossible for you, once here, not to change the future that will happen in some way. It might be the very smallest of ways, or you might return to find a world in which you do not even exist. Secondly, sending someone into the future is likely to be much more difficult, not to say more dangerous, than sending them to the past. At present, you see, all the opportunities for the future are equal; the future is not fixed. So even if you manage not to eliminate the possibility of _your_ future, finding out where to send you might prove impossible. And thirdly, the apparatus used to send you here operated on a very strong wish of yours to go here and change whatever it was that happened here that you've come to regret; to send you back would require and equally strong wish to go back. And while I am sure you have many reasons to want to return to your own time," he said, cutting Harry's protest short with a smile, "it is still in our very nature as humans to desire what we do not have more than the things that we've already acquired.

"However," he continued, when Harry looked dismayed, "I do believe that I've made the impossible quite possible before. So let us hope that this is yet another of those occasions. Now, for your disguise..." He tapped his cheek thoughtfully with a long finger.

"Disguise?" Harry blinked, confused by the sudden change of topic.

"Yes, disguise. Unless you want me to have you locked in here until we find a solution, we will have to disguise your appearance so that you do not look quite as much like your currently sixteen-year-old father. You should also have some rational reason to be present here at school. Perhaps a professor in training? You are a bit young, of course, but not young enough for it to be truly suspicious."

"But..." Harry protested weakly, "...I do not know very much about teaching, professor."

"Well, I do not thing that will surprise anyone. That is, after all, what you are here to learn." The familiar twinkle was back in Dumbledore's eyes now, something Harry found rather remarkable, since he'd just told him that he was going to die. On the other hand, he reminded himself, Dumbledore wasn't exactly young at this time either; the news of his future death would hardly come as a surprise to him. And the Dumbledore that Harry had known had at least never been afraid of death; it wasn't hard to imagine that this somewhat younger copy of him was no different.

"Okay, then," he said after a moment of thought. "Which subject should I help out in?" A thought struck him, "I have some experience in teaching Defence Against the Dark Arts," he added.

Dumbledore shook his head. "I do not know if this problem has been solved in your time, but the post as Defence teacher is currently jinxed, and I do not know if that jinx includes teachers in training. It would be unlucky if you were somehow harmed. Is there something else you think you master well enough to teach it."

Harry thought with a sigh that Hermione would have been so much better off in this position. And then, thinking of Hermione, an idea struck him. "I could help out in Muggle Studies," he offered, "I-" He was about to say that he had grown up with muggles, but checked himself just in time. Revealing this would be just as bad as telling Dumbledore that his parents were dead. "I have many muggle-born friends," he finished lamely.

"And not only friends I believe," Dumbledore said kindly. Harry wondered for a moment what he meant, then remembered what every friend of his parents had ever told him; remembered one of the reasons Snape had hated him so much.

"I do have my mother's eyes, don't I?" he said dryly.

"Quite so, yes. But I admire you for managing not to tell me," Dumbledore replied, sounding amused. So he thought that Harry's hesitation had come from reluctance to mention his mother? He supposed that was good.

"So? Is that a good idea?" he asked.

"Why, I think it's an excellent idea," Dumbledore said, nodding in approval. "I shall inform Professor Hunt at once. And when I return I think it is perhaps time to do something about your appearance, Mr Potter. And that too, come to think of it."

"What?"

"Your name, Mr Potter." And with a last twinkle of his eyes, the old man was gone.

* * *

Professor Hunt was a stern-looking, rather young woman with red hair and blue eyes that were like gimlets. She gave Harry an almost military once-over and arched an eyebrow at him with a small, controlled smile. "A bit young to want to become a teacher, aren't you?"

Harry thought that this was a bit rich of her, but didn't know what to reply.

Her smile turned into a smirk. "Before you ask, I was born with a mental age of forty-five. Anyway, considering how interested the average Hogwarts student is in muggle studies, I could certainly use some help."

"They're not very interested?" Harry asked, only mildly surprised. It didn't seem like wizards had ever been.

She gave him an odd look. "I do wonder what kind of school you come from, Mr Flinn. Muggle Studies is commonly known as 'snooze class'. Students take it because they won't have to make an effort, since no parent in ever upset about a poor grade in Muggle Studies. After all," she said, making a sour face, "it is not something they'll have any use of later in life."

Harry nodded. The attitude was hardly surprising. He'd never heard of anyone in his own year that actually _liked_ muggle studies. Hermione had probably – and ironically – been the keenest student in class, before she had to quit to save her own mental health. "Hopefully they'll learn that they were wrong later in life," he said, and Professor Hunt gave him a taut smile.

"So do I." She treated him to yet another long, shrewd gaze, before she nodded. "I think we're going to get along very well, Douglas Flinn."

* * *

The first lessons had gone surprisingly well, all things considered. Recalling his days teaching the DA really did help; he knew when encouragement was needed and which students needed a little extra attention. He also learned rather quickly to notice when someone was sleeping and to give them a sharp prod with his wand to jerk them awake.

Yet as he helped Professor Hunt prepare for the arrival of their sixth years, Harry was undeniably nervous. This was his father's year, even though he had no idea if James had in fact taken Muggle Studies. Professor Hunt had the student catalogue, but he hadn't dared ask her for it; it would be stupid to risk raising even the faintest hint of suspicion when he was soon going to find out anyway.

He'd seen his father around at school a couple of times, but hadn't had any reason to talk to him, and so he'd just watched him from afar. Outside of class, he never strayed far from his little gang, and they seemed content to roam around in each other's company or sit together in the library, probably plotting some mischief rather than studying. James and Sirius were louder and definitely more obnoxious than the other two, but all four of them seemed rather good at getting noticed.

As the students filed into room at the start of class, Harry picked out two of the marauders from their midst, but none of them were his father. Instead, Sirius and Pettigrew took seats at the front of the classroom. To his surprise, he saw Professor Hunt smiling rather warmly at the two of them, and they both grinned in response. Pettigrew nudged Sirius and whispered something to him, to which Sirius grimaced and mimicked swatting his companion over the head. Then they both laughed and took out their books.

"Those two are the sole reason I even bother," Professor Hunt mumbled out of the corner of her mouth. "It's nice to see some honest-to-god effort."

Harry knew enough about her by now not to take her words seriously. The reason she bothered was that she truly burned for the subject she was teaching, and believed in that the wizarding world would be a better place if the magical community could just be bothered to pay a little more attention to the people that they shared the world with. But nonetheless he was happy for her sake; she was a good teacher who deserved better students, and at least two were better than nothing. However, he knew he was it was going to be difficult, having Pettigrew at the front of the class every time they had sixth-years. Every time he had seen him so far, it had been enough to make him silently contemplate murder. The only thing that kept him from going mad was the thought of that back in his own time, the war was over, he was free, and Pettigrew had gotten what was coming for him. He didn't want to gamble that, not even for the satisfaction of hurting the one person that, save Voldemort, had hurt him more than anyone else.

He glared daggers at the back of the, at the time, younger boy's head when no one was watching, then started to prepare for class.

And already the scales were tipping, the future reshaping ever so slightly, but Harry wasn't aware of that yet. It would take a lot more for him to realise the impact that he would have on the future if he continued on this course.

* * *


End file.
